1. Field of the Invention
The present invention relates to an improved intake system for an engine of a vehicle, to an air cleaner housing which is a component of the intake system, and to a vehicle incorporating the intake system. More particularly, the present invention relates to an intake system including an air cleaner housing having at least one wall thereof formed with a stepped surface, and to an engine and a vehicle incorporating the same.
2. Description of the Background Art
There are several known intake systems for internal combustion engines. One example of an intake system, in which a number of noise absorbing members are arranged inside an intake muffler for reducing intake noises, is disclosed in Japanese Published Patent Document JP-A-62-255565. According to Japanese Published Patent Document JP-A-62-255565, as shown in FIG. 1 and FIG. 3 thereof, a muffler element 4, which performs a sound-absorbing function, is formed on one end portion of an intake muffler 3, and a filter element 9 which cleans (purifies) air is formed on another end portion of the intake muffler 3. The muffler element 4 includes a casing 18, a casing lid 19 which closes an opening formed in the casing 18, and three foamed-resin-made plates 13, 14, 15 arranged inside the casing 18 and the casing lid 19.
Another example of an intake system, in which plural diaphragms are arranged inside an air cleaner casing for reducing intake noises, is disclosed in the Japanese Published Patent Document JP-A-9-32667. According to Japanese Published Patent Document JP-A-9-32667, as shown in FIG. 1 and FIG. 2 thereof, an element 6 which is mounted on a mating portion of an air cleaner casing 5, and diaphragms 7a, 7b, which are mounted on a frame 6a of the element 6 such that the diaphragms 7a, 7b face upper and lower surfaces of the element 6 in an opposed manner with a distance defined therebetween, are stored in the air cleaner casing 5.
When the resin plates (foam plates) 13, 14, 15 are arranged inside the intake muffler 3 of the Japanese Patent Document JP-A-62-255565; or when the diaphragms 7a, 7b are arranged inside the air cleaner casing 5 of the Japanese Patent Document JP-A-9-32667, a number of components required for the intake system is required to be disadvantageously increased. Such increase in number of components has a drawback, because such increased number of components results in the intake system being large and complicated, and/or a weight of the intake system may be increased.
The present invention has been made to overcome such drawbacks of existing intake systems. Accordingly, it is one of the objects of the present invention to achieve a compact size of, and a reduction in weight of an intake system by reducing the number of components required for forming an intake system.